Salinity variation of south-western coastal region of Bangladesh in response to discharge from an upstream river

Long term variation in upstream water flow through the Ganges−Gorai river are affecting the salinity levels of south-western coastal region of Bangladesh. Salinity data for the Rupsha river was collected for several years to demonstrate the historical changes of salinity level in the south-western coastal region. Furthermore, discharge data of the Ganges and Gorai river were also collected to discuss the effect of upstream discharge on the variation of salinity level. This study also collected water and soil samples from different places of this region to measure the salinity level and compare the values with the standard ones. A decreasing trend in dry season Ganges-Gorai river flow was observed after the initiation of the Farakka barrage in 1975. Consequently, the south-western region underwent high salinity level. The Ganges sharing treaty in 1996 and dredging of the Gorai riverbed (GRRP-I and GRRP-II) in 1999 and in 2012 helped the region to recover from high salinity level for a certain period. The salinity level of the collected water samples was in alarming level but soil sample was not in so frightening condition in 2015. Results suggested that to maintain the salinity level of south-western region within the acceptable limit for drinking, fisheries, and cultivation purposes, approximately 80 m3/s Gorai river discharges required at dry season. To do that, it is necessary to ensure 1200 m3/s discharge through the Ganges river at the Hardinge Bridge point. To protect the vital south-western region, it becomes necessary to optimize flow augmentation in the Ganges-Gorai river and to continue the further phases of restoration project in the future.

Effects of different salinity levels on water quality, growth performance and body composition of Pacific white shrimp (Litopenaeus vannamei Boone, 1931) cultured in a zero water exchange heterotrophic system

The present study was aimed to evaluate the effects of different levels of salinity on water quality, growth performance, survival rate and body composition of Pacific white shrimp in a heterotrophic/biofloc technology (BFT). Shrimp post-larvae with an average weight of 74.46 mg were cultured in 300 L fiberglass tanks containing 130 L water at a density of 1 post-larva/L. Three treatments including different levels of salinity of 8, 21 and 32 ppt with three replicates were considered. The highest levels of body weight, growth rate, specific growth rate, increase in body length and survival rate were observed at high salinity level (32 ppt). The highest feed conversion ratio (FCR) and the lowest level of feed efficiency were obtained in shrimps cultured at lowest salinity level (P<0.05). Biochemical analysis of shrimp body composition showed an increase in protein, lipid and ash content as the salinity elevated (P<0.05). The zero-water exchange system used in this study had no significant effects on water quality parameters. The results of the present study concluded that high salinity level (32 ppt) improves the growth and survival of the biofloc supplemented Pacific white shrimp in a BFT system.

Evaluasi Ketahanan Sumber Daya Genetik Kedelai terhadap Cekaman Salinitas

Soybean (Glycine max (L.) Merr.) is sensitive to salinity stress. The availability of soybean cultivar tolerant to salinity stress is the main key of succeeding of soybean cultural practice on saline affected land. Objective of the research was to evaluate the resistance of soybean germplasms to salinity stress. The research was conducted on saline affected soil in Lamongan District during the dry season (May-August) 2016. Nineteen soybean genotypes that were selected from previous salinity test in the green house were reevaluated in the field using a randomized block design with three replications. Wilis cultivar (sensitive to salinity) used as check. Variable observations consisted of soil properties before planting, number of plant grow at 13 and 41 days after sowing (DAS), plant height at 41, 56 and 71 DAS, chlorophyll content index at 27, 41 and 56 DAS, soil EC at 71 DAS, number of harvested plants, yield and yield components. The results showed that among 19 genotypes tested, only five genotypes that survived up to harvest with plant population 30-50% at high salinity level. Salinity reduced plant population more than 50%, and plant height only 50% from its normal height. Based on soil EC, plant population at harvest, and yield, genotype Karat 13, Grayak 3 and Grayak 5 were identified adaptive to high salinity level with soil EC 11,7-14,4 dS/m, while MLGG 0160 were identified adaptive to moderate salinity level with soil EC up to 9,1 dS/m.

Effects of NaCl, CaCl2 and their Combination of Salt on Seed Germination and Seedling Growth of Lycopersicum esculentum L.

To compare the effect of NaCl, CaCl2 and their combinations on germination and early seedling growth stages of Lycopersicum esculentum L., were studied under pot experiments 2008. Results indicated that significant increases were recorded in percentage of germination, seedling fresh and dry weights, seedling length, water content, catalase activity and photosynthetic pigments (chlorophyll a, b and total chlorophylls as well as carotenoids) under the low level concentration (20 mM) of NaCl or CaCl and their combination (1:1). On other hand increasing salt concentration in nutrient solution caused significant decrease in all of these parameters. The great reduction occurred under high salinity level of NaCl (50 mM). Meanwhile, peroxidase activity increased significantly with increasing salinity levels from 20 mM to 50 mM of both applied salinity types. Besides, peroxidase activity under NaCl salinity showed a marked increase followed by NaCl + CaCl2 (1:1) and CaCl2 at 50 mM.

Test the Development in Salt Tolerance in Two Selected Genotypes of Wheat

The genetic development for salt tolerance in wheat is very important approach for the plant breeder to overcome salinity problem. Estimation of salt tolerance by two selected genotypes of wheat (4H, N5) was conducted in plastic house as compared with the local cultivars Tamoz 2 to know the development that happened in salt tolerance in these genotypes through the plant breeding programs. The experiment was conducted in pots using four salinity levels (2, 5, 10, 15)ds/m. The experimental design was RCBD with three blocks. Results indicated that both selected genotypes were significantly superior in all measured characters to check cultivar at all salinity levels. There were differences between the two selected genotypes in different traits, but not significant especially at high salinity levels. At these salinity levels, the selected genotypes had more growth in shoots and roots. The differences between the two selected genotypes and the check cultivar in all characters increased in high salinity level. In conclusion, there were genetically improvements with aspect to salt tolerance achieved in selected genotypes through breeding and improvement programs.